sim900a_send_cmd(u8 *cmd,u8 *ack,u16 waittime)中waittime减到0不会跳出while，跳出之后res=1了，就返回失败了。

freewayflyer

[mw_shl_code=c,true]u8 sim900a_send_cmd(u8 *cmd,u8 *ack,u16 waittime) { u8 res=0; USART2_RX_STA=0; if((u32)cmd<=0XFF) { while(DMA1_Channel7->CNDTR!=0); //?????¨??7?????ê?? USART2->DR=(u32)cmd; }else u2_printf("%s\r\n",cmd);//·????ü?? if(ack&&waittime) //?è?????????? { while(--waittime) //?????????± { delay_ms(10); if(USART2_RX_STA&0X8000)//?????????????????á?? { if(sim900a_check_cmd(ack))break;//???????§???? USART2_RX_STA=0; } } if(waittime==0)res=1; } return res; } [/mw_shl_code]

sim900a_send_cmd(u8 *cmd,u8 *ack,u16 waittime)中waittime减到0不会跳出while，跳出之后res=1了，就返回失败了。难道waittim有点矛盾吧     还有就是我看程序里是不管收不收得到应答都会消耗waittime*10ms，难道waittime不是0就能跳出while

login_FAE

等待时间内   没有收到数据  就返回 接收失败
等待时间内     收到数据就跳出循环

cms277415310

*ack（应答结果） 何时 传到USART3_RX_BUF[]中的  一直没看出来